ideas for a watertight fish tank top

Instead of using a sealant on the wire mesh top that comes standard with most fish tanks I was wondering if anyone has an idea for how to create a top that is airtight and ideally easy to cut holes in without breaking the whole piece?

I had a page bookmarked and intended to order from them but then the pc broke and I've lost the link.
They sell plastic panels of various size and thickness.
I'm not quite sure what it is you're trying to do .

Im trying to replace the top on a fish tank. The current one produces a watertight seal only because the thing is covered in sealant around the edges. The problem is that the motor (in the tank) keeps breaking down and I have to tear the whole thing apart to get at it.

I'd like to replace the top with something I don't have to use sealant on so that I can take it off and put it back on as I need to repair the motor. I was thinking of using painted plexiglass (to keep the light out) but I don't think that will be airtight or easy to remove without using sealant.

It needs to be airtight because the sprayers shoot water at the top and If water leaks even a little I have to refill the tank multiple times a day.

is this for fish or?....an animal?